1. Field of the Invention
The present invention relates to an oxide superconducting wire, a method of preparing the same, and a method of handling the same, and more particularly, it relates to improvement for distortion resistance of critical current density in an oxide superconducting wire.
2. Description of the Background Art
In recent years, superconducting materials of ceramics, i.e., oxide superconducting materials, are watched as materials exhibiting higher critical temperatures. In particular, those of yttrium-based, bismuth-based and thallium-based, which exhibit high critical temperatures of about 90K; 110K. and 120K. respectively, are expected as practicable superconducting materials.
In relation to a method for obtaining an oxide superconducting wire, such as a long superconducting wire or a superconducting pattern which is wired on a proper substrate, using a superconductor of such an oxide superconducting material, known is a method of covering raw material powder with a metal sheath and heat treating the same for bringing the raw material powder into a desired superconducting material, thereby preparing an oxide superconducting wire comprising a superconductor covered with the metal sheath. The as-formed superconducting wire is applicable to a cable, a bus bar, a current lead, a magnet, a coil or the like.
In order to apply the aforementioned superconducting wire to a cable, a magnet or the like, it is necessary to attain a high critical current density, in addition to a high critical temperature. In particular, it is necessary to ensure a critical current density required under a magnetic field which is applied to the superconducting wire, while such a high critical current density must be maintained under distortion which is applied to the superconducting wire.
However, a superconducting wire containing an oxide superconductor is so far inferior in distortion resistance of critical current density that the critical current density is reduced when the superconducting wire is bent at a certain curvature level, for example.